Rechargeable lithium-ion battery technology is an attractive technology for broader adoption in portable power systems because of its light weight, high voltage, high electrochemical equivalence and good conductivity. With the prospect of broad use of battery power in automotive propulsion systems, whether hybrid or plug-in or other technology, many efforts have been undertaken to improve lithium-ion batteries to meet the expected market needs and to capture as much of the substantial reward and value that will likely come from broad implementation. One development that is likely to be adopted in commercial lithium-ion batteries is carbon coated graphitic powders for use on the anode or negative electrode of lithium-ion batteries. The graphite provides efficient intercalation and de-intercalation of lithium ions while the carbon coating enhances electrical conductivity and protection for the underlying graphite from the electrolyte in a battery. High first cycle efficiency and long cycle life are better enabled with such materials in the anode.
However, as with almost anything, improved performance or improved characteristics such as lighter weight are always desirable and there is always a drive toward providing high performance at lower cost. With the current process of making carbon coated graphitic particles, the starting material is obtained from petroleum coke. The coke may be calcined prior to coating or may be calcined after it is coated. The coating is applied by a selective precipitation method where carbon residue forming materials, preferably a high molecular weight petroleum pitch, is dissolved in a solvent. The coke particles are added to the pitch solution and the solvent strength is altered by the addition of more solvent or other liquids to cause the higher molecular weight species in the pitch to precipitate on the particles. The coated coke particles are then removed from the coating process and stabilized at an elevated temperature in the presence of oxygen, and graphitized in an inert environment at a temperature higher than the stabilization temperature. This process is generally described in commonly own U.S. Pat. No. 7,323,120 issued Jan. 29, 2008.
It is highly desirable to make really small particle size graphitic materials and be able to tailor the particle size distribution so that a predetermined range of particle sizes with a predetermined average or mean could be delivered to a battery manufacturer per the manufacturer's specifications. To be able to produce such materials with low cost precursors in a fast and inexpensive process would be even more ideal.